If "I get x2 too" means that x2 appears in the DNS zone at no additional charge, then I agree, a language tag would be useful.
Read the JET IDN Admin.
Depending on what kind of variants, it may or it may not end up in the zonefile. As for the question involving cost, that is left out of the document *intentionally* because we dont think IETF is the forum to discuss that.
--Paul Hoffman, Director --Internet Mail Consortium